The U.S. labor market's long, slow recovery slowed further in July—and many of the jobs that were created were in low-wage industries.

Employers added a seasonally adjusted 162,000 jobs in July, the fewest since March, the Labor Department said Friday, and hiring was also weaker in May and June than initially reported. Moreover, more than half the job gains were in the restaurant and retail sectors, both of which pay well under $20...